The present invention relates to a disk cleaner for removing flaws on a disk or dirt adhered to the surface of a disk, such as an optical disk or a photomagnetic disk of the type employed as an information recording medium, and in particular to a disk cleaner which polishes a soiled surface of the disk by pressing a rotating polishing member, such as a buffing wheel, against the soiled surface of the disk.
In recent years, various kinds of disks, such as a laser disk, a CD (compact disk), CD-ROM, DVD, etc., are extensively employed as an information recording medium for use in audio and video recording or in a computer. When a flaw is present or dirt is adhered to the surface, in particular, of the recording surface of these disks, not only is the external appearance of the disk diminished, but also the recorded data of the flawed portion or soiled portion may not be properly read out, thereby making it difficult or impossible to properly reproduce the recorded data.
Under the circumstances, such a flaw or dirt that has been adhered to the surface of the disk has been conventionally removed manually using a cloth. However, such a manual operation is troublesome and takes time, and additionally, it is difficult, by such a manual operation, to sufficiently remove the flaws or the dirt. In particular, in a shop that handles secondhand CDs or a library where a large number of disks are retained and frequently replaced or loaned out, the removal of flaws or dirt adhered to the surface of the disk involves a lot of labor. Therefore, there has been a long felt need for a device to mechanically and automatically remove flaws on or dirt adhered to the surface of the disk in place of the conventional manual removal of such flaws or dirt.
In response to such a demand, a disk cleaner has been proposed in Japanese Patent Unexamined Publication H7-122038, wherein a peripheral surface of a cylindrical polishing member, such as a buffing wheel, is pressed against the surface (recording surface) of a disk while the disk is caused to rotate, thereby polishing the recording surface.
However, the disk cleaner proposed in the aforementioned Japanese Patent Unexamined Publication is subject to the following problems.
(1) Since the peripheral surface of the polishing member is engaged with the surface to be polished of the disk (hereinafter simply referred to as "the surface of the disk"), or in other words, since the rotational axis of the polishing member is disposed parallel with the surface of the disk at the time of polishing, the distal end portion of the polishing member is always engaged with a radially inner portion of the disk while the proximal portion of the polishing member is always engaged with a radially outer portion of the disk. More specifically, all portions of the disk in the radial direction are always engaged with the same portions of the peripheral surface of the polishing member. In this case, since the circumferential speeds of rotation of portions of the disk farther from the center of the disk are higher than those of the portions of the disk closer to the center, a waviness is more likely to be generated all over the surface of the disk unless the cylindricity of the polishing member as well as the parallelism between the axis of rotation of the polishing member and the surface to be polished are properly maintained.
(2) Although it is generally preferable at the time of polishing of the disk to use two kinds of polishing member, i.e. a polishing member for rough-polishing (flaw removal) and a polishing member for fine-polishing (finishing), the disk cleaner proposed in the aforementioned Japanese Patent Unexamined Publication is arranged such that only one polishing member can be engaged with the surface of the disk, thus necessitating a frequent exchange of two kinds of polishing members, i.e., a polishing member for flaw removal and a polishing member for fine-polishing, which is troublesome for a worker using the disk cleaner.
(3) It is impossible, in the case of the disk cleaner proposed in the aforementioned Japanese Patent Unexamined Publication, to adjust the amount of pressure of the polishing member against the surface of the disk. Since the polishing member is gradually abraded and deformed due to the use thereof in operation, the pressure of the polishing member against the surface of the disk becomes insufficient unless the pressing force of the polishing member against the surface of the disk is properly adjusted, thus making it impossible to properly perform the removal of flaws and dirt from the surface of the disk.
(4) According to the disk cleaner proposed in the aforementioned Japanese Patent Unexamined Publication, it is required, when mounting or dismounting the disk or of exchanging one polishing member for another, to shift the disk-retaining arm, together with the disk-driving motor, in the radial direction of the disk (horizontal direction), thus involving a troublesome operation.
(5) Although it is required that the cylindricity of the polishing member as well as the parallelism between the polishing member and the surface to be polished be properly maintained, the disk cleaner proposed in the aforementioned Japanese Patent Unexamined Publication fails to take any suitable measures to meet these requirements. As a result, the pressure of the polishing member against the surface of the diskmay become non-uniform, thus making it impossible to uniformly polish the surface of the disk.